Studies on Reactive sintering behavior of milled nano Mo/Si₃N₄ powder mixture

Abstract

Attempts are made to fabricate Si₃N₄ - MoSi₂ in situ composites by reactive milling and reactive sintering of milled powders. 10 hours of milling Mo and Si₃N₄ powder mixtures shows the substantive increase in reactivity, which reaches to maximum after 30 hours of milling. The milling however even up to 104 hours does not by itself lead to the formation of MoSi₂ phase. The pyrolysis of milled powder mixture with varying amount of sintering aid in the temperature range of 1000-1400 °C indicates that MoSi₂ phase forms only at 1400 °C in argon, whereas 1350 °C in vacuum. SEM analysis of milled and pyrolised samples shows uniform distribution of 0.5-1 micron size MoSi₂ in Si₃N₄ matrix. Longer hours of milling often leads to formation of SiC and it also played by large amount of WC contaminations.